Stethoscope



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STETHOSCOPE v Filed March 3, 1934 Inventor:

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- UNITED STATES PATENT OFFICE signor to General Electric Company, a corporation of New York Application March 3, 1934, Serial No. 713,908

'sciaims.

This invention relates to stethoscopes and has for its object to provide an electrically operated stethoscope which will be much more sensitive than such instruments as are already in use.

This instrument consists in providing means for transmitting sounds from the interior oi the human body, such as the beating oi the heart or the passage 01' air through the lungs, to a microphone -and in providing means for amplifying these sounds to any desired extent.

The accompanying drawing illustrates one method of carrying this invention into eii'ect.

In this form I provide a microphone i which is preferably of the moving iron or reed type. This microphone is mounted in resilient material such as spongy rubber 2 in an iron box 3 for screening purposes. The reed 4 is connected either directly or through a resilient support 5 to a rod 8 which carries at its outer end a. disc I 01' heat insulating material, which conveys the impulses from the body to the microphone by direct contact. This contact disc is protected by a heat insulating cylinder 8 which surrounds it and normally projects a slightly greater distance from the casing oi the instrument than the disc. Heat insulating material is used in preference to metal in order to prevent cold metal coming in contact with the body. The insulating cylinder slides inside a metal cylinder 6 secured to the casing I of the instrument and is normally held in its outermost position by means of springs it. The insulating cylinder may be held against rotation by means of one or more guide pins ii operating in longitudinal grooves or slots iia formed in the cylinder, and these pins may be utilised to limit the outwardmovement o! the cylinder.

The microphone is connected through a switch including a pair of contacts I! and through leads II to an amplifier represented by the rectangle ii, the output oi which may be connected to a telephone or other suitable sound receiving device as indicated by the numeral ll.

n operation the insulating cylinder 0 is pressed W the body or the .patient and slides into the metal cylinder I against the actioii oi the springs ll normally'holdingit in its outermost position. This movement 01' the cylinder ilrst brings the contact disc I into contact with the patient's bodyand the further limited t insures good, contact which will always be substantially the The inward} tortheinsulatingcylinderalsocioses thehlli'otemtaotsliloeatedlnthefllament" circuitottheamplinerllandao'uiablesthe Great Britain March 8, 1938 atre, a loud-speaker may take the place of the 10 head-phones.

,What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a stethoscopic apparatus, a microphonic device including a movable member, a disc adapt- 16 ed to be pressed into contact with a body thereby to be vibrated by sounds to be transmitted from said body, means to transmit the vibrations of said disc to said movable member, and means to maintain substantially constant the pressure oi said 20 disc against said body. C

2. In a stethoscopic apparatus, a microphonic device having a movable iron member, a disc adapted to be brought into contact with a body thereby to be vibrated by sounds to be tram initted from said body, means to transmit the vibrations of said disc to said movable iron memher, a protecting sleeve surrounding said disc, and a circuit closing means, said sleeve being slidable to uncover said disc and to operate said circult closing means.

3. In a stethoscopic apparatus, a microphonic device having a movable reed, a disc adapted to be pressed into contact with a body therebyto be vibrated by sounds to be transmitted irom said body, means to transmit the vibrations oi said disc to said reed, and a protecting sleeve surrounding said disc, said sleeve being slidable to uncover said disc, and means to limit the sliding movement of said sleeve whereby the pressure oisaiddisconsaidbody issubstantiallyuniform.

4. In a stethoscopic apparatus, a microphone having a movable member, a contact member adapted to be pressed asainst'a body thereby to be vibrated by sounds tobe trammittcd from said body, means to connect said contact member to said movable member, and a protecting member surrounding said contact member and slidable a predetermined distance to uncover said contact'member whereby the pressure of said contact member on said body is substantially uniform.

5. In a stethoscopicapparatus, a microphone. having a movable member, a contact umber as distancewtwardlytromsaidcasinx,andmeans' to limit the travel ,0! said protecting member toward said casing whereby the pressure of said contact member against said body is maintained substantially unitorm when said stethoscopic ap- 5 paratus is applied to said body.

cyan. ARTHUR Mason. 

